Torsion beam axles of the type concerned have characteristics common to both trailing arm axles and conventional solid axles. They are usually of simple design and consist essentially of two trailing arms which are resistant to torsion and bending, and which are connected to one another by a cross-member that is also resistant to bending but is compliant to torsion. Due to the torsionally compliant design of the cross-member, the wheel-carrying trailing arms can twist relative to one another. At the same time, the cross-member of the torsion beam axle acts as a roll stabilizer for the vehicle. In general the torsion beam axle enables good straight-ahead driving behavior, which is ensured by the fact that the two trailing arms guide their respective wheels firmly in the longitudinal direction. During compression and rebound bouncing movements on the same side, the trailing arms pivot with the cross-member like a horizontal pendulum about the articulation point on the bottom of the vehicle, so that the wheel track changes only very slightly. When bouncing on alternate sides, the cross-member twists and thereby compensates for height differences between the two wheels.
For the rear axle of a vehicle torsion, beam axles are an inexpensive solution since they largely consist of only one welded assembly with two rubber mountings. Moreover, this type of axle is simple to assemble and can be fitted on the motor vehicle in a space-saving manner, so many passenger automobiles up to the compact class are built with axles of this type.
However, there are known to be limitations with regard to the driving dynamics of a torsion beam axle, particularly due to the design-related, unfavorable action of lateral forces which results in a tendency toward lateral force overcompensation and more difficult isolation of vibrations. A torsion beam axle of the type concerned for a motor vehicle is known from DE 10 2008 002 639 A1. This torsion beam axle comprises a cross-member which couples the bouncing movements of the rear wheels of the motor vehicle with one another in a torsionally compliant manner by means of trailing arms. At its ends on each side of the vehicle, the cross-member is connected to a trailing arm on which, in each case, a vehicle wheel carrier is fixed. In this prior art, to hold the vehicle wheel concerned and to connect the trailing arm and the vehicle wheel, a wheel carrier is provided, which allows steering movement of the wheel concerned by virtue of a pivoting connection to the trailing arm. The associated steering movement is produced by an actuating mechanism that is connected to the wheel carriers by a tie rod.
Thus, the torsion beam axle known from the document enables the track angle of the rear wheels to be actively adjusted in order, in particular, thereby to improve the driving dynamics of the torsion beam axle. However, with the torsion beam axle known from that document—depending on the positioning and articulation of the tie rod—the arrangement of the tie rod and actuating mechanism may be kinematically inappropriate and, depending on the (sometimes) unilateral bouncing of the torsion beam axle, this can result in particular in track angle differences, i.e. erroneous steering angles of the steered rear wheels.